The present invention relates to plug-in couplings for pressure application systems having a receiving component with an opening and a holding element, a connector component with a connecting shaft, an expanding cylinder supported on the connecting shaft between a radial step and a limit stop, and a spring unit initially supported on the expanding cylinder.
With the conventional plug-in couplings, the connecting shaft of the connector component can be inserted into the opening of the receiving component along an insertion direction thereby engaging the radial step with the holding element to prevent loosening of the connector component from the receiving component.
The conventional plug-in coupling can preferably be used for pipelines and hose pipes in low-pressure systems, such as motor vehicle braking systems, and are well known from the German patent DE 28 24 943 C2. The spring unit serves to generate an axial prestress in the plug-in connection. To release a conventional plug-in connection, the expanding cylinder can be guided into the opening, in a insertion direction, which is opposite the action of the spring unit, and can prop open the holding element to release the arrested radial step of the connecting shaft. In these couplings, different designs for constructing the spring unit are known from the cited German patent and from EP-A-0 005 865. Thus the spring unit can be designed as a helical spring, as a cylindrical protecting sleeve, or as a cylinder of rubber elastic material with an indentation around its perimeter for adjusting the spring characteristic. The conventional plug-in couplings have proven themselves in practice in numerous embodiments. There is room for improvement, however, especially with respect to ease of assembly.
It is the object of the present invention to create a plug-in coupling that has high operational and functional reliability and is simple and economical to manufacture. This is achieved by a plug-in coupling for pressure application systems in which the spring unit can be radial-elastically widened in such a way that it can be guided over the expanding cylinder's largest peripheral contour against the direction of insertion.
With the design of the spring unit in accordance with the invention, this spring unit can be removed from the region of the expanding cylinder to release an existing plug-in connection of connector and receiving components, so that the expanding cylinder advantageously does not have to be pressed into the opening in a direction against the action of the spring unit.
In contrast to the conventional plug-in couplings, the spring unit can be so advantageously designed in this respect that, with the spring unit not removed, the expanding cylinder cannot be pressed so far into the opening in the insertion direction against the action of the spring unit that the arrest is released. In this way, the spring unit also operates simultaneously as a safety catch against unintentional loosening of the connection, so that other safety catches do not have to be provided.
An O-ring can be used as the spring unit in the preferred design. This O-ring preferably works as a multifunction element, which, in addition to its function of applying the axial prestress (spring function) in the plugged-in state through positive fit with the expanding cylinder, also operates as a safety catch against unintentional loosening of the connection (locking function), absorbs vibrations arising from operating conditions, and seals against the entry of dirt.
To simplify its assembly onto the connector component, the expanding cylinder can have a longitudinal slit, preferably enabling it to be radial-elastically widened, whereby an O-ring introduced as the spring unit can then also produce radial prestress of the expanding cylinder, fulfilling another function, and hold the longitudinal slit closed.
Further preferred developmental characteristics of the invention are contained in the appended claims and the following description: